Dual substrate loadlock process equipment

ABSTRACT

One embodiment relates to a loadlock having a first support structure therein to support one unprocessed substrate and a second support structure therein to support one processed substrate. The first support structure is located above the second support structure. The loadlock includes an elevator to control the vertical position of the support structures. The loadlock also includes a first aperture to permit insertion of an unprocessed substrate into the loadlock and removal of a processed substrate from the loadlock, as well as a second aperture to permit removal of an unprocessed substrate from the loadlock and insertion of a processed substrate into the loadlock. A cooling plate is also located in the loadlock. The cooling plate includes a surface adapted to support a processed substrate thereon. A heating device may be located in the loadlock above the first support structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 11/613,556, filed Dec. 20, 2006, which is a continuation ofU.S. patent application Ser. No. 10/842,079, filed May 10, 2004 andissued as U.S. Pat. No. 7,641,434, which is a continuation of U.S.patent application Ser. No. 09/464,362, filed Dec. 15, 1999 and issuedas U.S. Pat. No. 6,949,143, all of which are herein incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to substrate processing systems, and, moreparticularly, to loadlock systems for handling substrates.

BACKGROUND OF THE INVENTION

Substrates such as, for example, glass panels used in applications suchas television and computer displays may be fabricated using sequentialsteps including physical vapor deposition (PVD), chemical vapordeposition (CVD), etching, and annealing to produce the desired device.These steps may be carried out using a variety of processing systemshaving multiple chambers. One such system is known as a “cluster tool”.A cluster tool generally includes a central wafer handling module ortransfer chamber and a number of peripheral chambers including aloadlock chamber through which workpieces are introduced into andremoved from the system and a plurality of other chambers for carryingout processing steps such as heating, etching, and deposition. Thecluster tool also generally includes a robot for transferring workpiecesbetween the chambers.

The processing of large glass substrates used for displays is in someways similar to the processing of other types of substrates such assemiconductor wafers. Such glass substrates, however, are often largerthan typical silicon wafers. For example, glass substrates may havedimensions of 550 mm by 650 mm, with trends towards even larger sizessuch as 650 mm by 830 mm and larger, to permit the formation of largerdisplays. The use of large glass substrates introduces complexities intoprocessing that may not be present when processing other types ofsubstrates. For example, in addition to their size, glass substratesused for displays are typically rectangular in shape. The large size andshape of glass substrates can make them difficult to transfer fromposition to position within a processing system when compared withsmaller, circular-shaped substrates. As a result, systems for processingglass substrates generally require larger chambers, apertures, andtransfer mechanisms. In addition, it is known to utilize large cassettesholding approximately 12 substrates within the loadlock in order tosupply a large number of substrates to the processing chambers for batchprocessing operations. The need for larger chamber sizes to handle largesubstrates, as well as the use of large substrate cassettes in theloadlock, also leads to a requirement for larger and more powerfulvacuum pumps, power supplies, control mechanisms and the like and acorresponding increase in system cost.

In addition, glass substrates often have different thermal propertiesthan silicon substrates. In particular, glass generally has a relativelylow thermal conductivity, which can make it more difficult to uniformlyheat and cool the substrate. Temperature gradients may occur across theglass substrate, which can lead to undesirable stresses in the substrateupon cooling. The heat loss near the substrate edges tends to be greaterthan near the center. Temperature gradients during processing can alsoresult in the components formed on the substrate surface havingnon-uniform electrical (and structural) characteristics. As a result, tomaintain adequate temperature control, heating and cooling operationsare often performed relatively slowly. As the system components becomelarger in size, these steps may be slowed even more due to the longertime it generally takes to heat and cool large components in a largevolume chamber. These slow operations tend to lower the systemthroughput.

SUMMARY OF THE PREFERRED EMBODIMENTS

Certain embodiments of the present invention relate to loadlock devicesfor use in substrate processing systems that are relatively compact insize and that can achieve substrate transfer, cooling and/or heatingoperations in an efficient manner.

In one embodiment, a loadlock chamber comprises a chamber body having afirst and second substrate access port, a first plurality of supportpins movably disposed in the chamber body and arranged to support afirst substrate thereon, a second plurality of support pins movablydisposed in the chamber body and arranged to support a second substratethereon, and a cooling plate disposed in the chamber body below thefirst plurality of support pins and stationary with respect to thechamber body.

In another embodiment, a loadlock chamber comprises a chamber bodyhaving a first and a second substrate access port, a first plurality ofsupport pins movably disposed in the chamber body and arranged tosupport a first substrate thereon, a second plurality of support pinsmovably disposed in the chamber body and arranged to support a secondsubstrate thereon, and a cooling plate fixed to the chamber body at aposition below the first plurality of support pins.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described with reference to theaccompanying drawings which, for illustrative purposes, are schematicand not drawn to scale.

FIG. 1 is a top schematic view of a cluster tool including a loadlock,transfer chamber, and processing chambers according to an embodiment ofthe present invention.

FIG. 2 is a cross-sectional view of a portion of the loadlock of FIG. 1in accordance with an embodiment of the present invention.

FIG. 3 is a perspective view of a loadlock according to an embodiment ofthe present invention.

FIG. 4 is a perspective view of the loadlock of FIG. 3 including anouter body section around an interior compartment according to anembodiment of the present invention.

FIG. 5 is a perspective view of the loadlock of FIGS. 3 and 4 includinga cover portion and a lower portion according to an embodiment of thepresent invention.

FIG. 6A is an exploded view of certain interior components of a loadlockaccording to an embodiment of the present invention.

FIG. 6B is a perspective view of some of the loadlock components of FIG.6 when assembled together according to an embodiment of the presentinvention.

FIGS. 7A-F illustrate a processing scheme in accordance with anembodiment of the present invention.

FIG. 8 is a perspective view of a portion of a loadlock system in aload/unload condition in accordance with an embodiment of the presentinvention.

FIG. 9 is a perspective view of a portion of a loadlock system in a cooldown condition in accordance with an embodiment of the presentinvention.

FIG. 10 is a cross-sectional view of a cooling plate with a coolantcarrying channel therein in accordance with an embodiment of the presentinvention.

FIG. 11 is a cross-sectional view of a cooling plate with acoolant-carrying channel at a bottom portion of the cooling plate inaccordance with an embodiment of the present invention.

FIG. 12 is a cross-sectional view of a middle plate with a coolantcarrying channel therein in accordance with an embodiment of the presentinvention.

FIG. 13 is a cross-sectional view of a middle plate with a coolantcarrying channel at an upper portion of the middle plate in accordancewith an embodiment of the present invention.

FIG. 14 is a top view of a plate having a high emissivity area inaccordance with an embodiment of the present invention.

FIG. 15 is a cross-sectional view of a cooling plate and substratesupport system according to an embodiment of the present invention.

FIG. 16 is a top cross-sectional view of a cluster chamber according toan embodiment of the present invention.

FIG. 17 is a top cross-sectional view of a cluster chamber according toan embodiment of the present invention.

DETAILED DESCRIPTION

Certain preferred embodiments relate to loadlock systems and methods ofoperation. These loadlock systems may be used as part of a largercluster type processing system. As illustrated in FIG. 1, one embodimentincludes a cluster system having a central substrate handling module ortransfer chamber 10, a number of peripheral process chambers 20, and atleast one loadlock mechanism 30 for inserting substrates into the systemand removing substrates from the system. The central transfer chamber 10may include a robot 40 therein for picking up and delivering substratesbetween the various chambers. The term substrates includes substratesformed from a variety of materials including, but not limited toglasses, semiconductors, ceramics, metals, composites, and combinationsthereof.

A preferred embodiment of the loadlock 30 is illustrated in thecross-sectional view of FIG. 2. The loadlock 30 preferably includes adual substrate cassette 50, with an upper slot 51 for holding anunprocessed substrate and a lower slot 53 for holding a processedsubstrate. The upper slot 51 may preferably be located between an upperplate 54 and a middle plate 56 of the cassette 50. The lower slot 53 maypreferably be formed between the middle plate 56 and a cooling plate 52,above a lower plate 76 of the cassette 50. The plates 54, 56 and 76 areassembled to form the cassette 50. The cooling plate 52 is almostentirely located within the cassette 50. However, it is preferably notconnected to the cassette 50. Instead, flange portions 100, 102 of thecooling plate 52 are preferably attached to a frame member 64 thatsurrounds the cassette 50. This structure enables the cassette 50 tomove independently of the cooling plate 52 by coupling the cassette toan elevator 58 (FIG. 3) through shaft 128. By moving the cassette 50independently of the cooling plate 52, a substrate on supports 78, 80within the lower slot 53 can be lowered onto and raised off of thecooling plate 52 by moving the cassette.

In certain preferred embodiments, a substrate on the cooling plate 52may be cooled by positioning the cooling plate (with the substratethereon) and the middle plate 56 very close to one another. Bysandwiching the substrate between the cooling plate 52 and middle plate56, the substrate can be cooled in an efficient manner. As will bediscussed in more detail later, both the middle plate 56 and the coolingplate 52 may be water cooled and may have a high emissivity surfacearea.

Progressive views of the loadlock 30 are illustrated in FIGS. 3-5. Thecassette 50 may include an opening 62 for viewing the cassette interiorduring operation. FIG. 4 shows the loadlock 30 of FIG. 3, furtherincluding the loadlock body portion or frame member 64 surrounding thecassette 50. A window 66 may be provided for viewing the interior of thecassette through opening 62, and a door 68 may be provided for accessingthe interior of the loadlock to insert and remove substrates. Theelevator 58 may be positioned below the cassette 50 and used to move thecassette 50 relative to the cooling plate 52 and frame member 64. Asshown in FIG. 2, the elevator 58 may include a shaft 128 attached to thebottom of the cassette 50 through a connection such one or moreconnectors 130 and plate 132. The connectors 130 may be designed to beadjustable so that the cassette 50 can be leveled if it becomesmisaligned. Alternatively, the shaft 128 may be directly connected tothe cassette 50.

FIG. 5 shows the loadlock 30 of FIGS. 3 and 4, further including a toppressure vessel portion or top cover 70 and a lower pressure vesselportion or bottom cover 72 to define the loadlock chamber region. Thetop cover 70 and bottom cover 72 may be any suitable structure capableof maintaining appropriate vacuum or other desired pressure conditionsand be capable of surviving elevated temperatures such as thoseencountered during substrate heating. The loadlock 30 may also include awheeled frame structure 74 for supporting and moving the loadlock 30.

FIG. 6 a illustrates an exploded view of certain components in theloadlock 30 including components from the cassette 50, the cooling plate52 and the frame member 64. FIG. 6 b illustrates the cassette 50assembled within the frame member 64. The frame member 64 includesopenings 96 and 98 on opposite sides, through which substrates areinserted into and removed from the loadlock. Opening 96 may be on theatmospheric side of the loadlock, and opening 98 may be on the transferchamber side of the loadlock.

The lower plate 76 of the cassette 50 preferably has a support structureincluding the supports 78, 80 thereon for supporting a substrate 82. Thecooling plate 52, (located above the lower plate 76) may includeapertures 84, 86 through which the supports 78, 80 may extend to supportthe substrate 82 in the lower slot 53. The middle plate 56 preferablyhas a support structure including supports 88, 90 thereon for supportinga substrate 92 in the upper slot 51. Above the middle plate 56 (and thesubstrate 92) lies the upper plate 54 and heating device 94. The heatingdevice 94 may include, for example, a resistance element or a heatinglamp. Alternative embodiments may omit the upper plate 54 and/or theheating device 94.

As illustrated in FIG. 6 a, the heating device 94 may fit into a recessin the upper plate 54 so that it moves with the cassette 50 and isalways positioned close to the upper support structure. Alternatively,the heating device 94 may be positioned above the upper plate 54 asillustrated in FIG. 2 or at some other position in the loadlock. Onepreferred use for the heating device is to preheat an unprocessedsubstrate prior to transferring the substrate to other chambers.Preheating the substrate may free up one or more processing chamberpositions in the system which would otherwise be used as heatingchambers to heat the unprocessed substrate. By preheating the substratein the loadlock, such heating chambers may be eliminated. Embodimentsmay heat the substrate to a desired temperature depending on theparticular processing operation such as, for example, a temperature inthe range of approximately 100 degrees Celsius to 500 degrees Celsius orhigher. It may be possible to also use the loadlock for other types ofheating operations, such as annealing or ashing, if desired. For certaintypes of high temperature processing or processing in which thesubstrate is heated in between other processing steps, separate heatingchambers may still be required.

FIGS. 7 a-f schematically illustrate several components of a loadlock asused during one possible processing embodiment. Certain component sizesand shapes have been altered relative to earlier figures forillustrative purposes. The components illustrated include the lowerplate 76, the cooling plate 52, and the middle plate 56. Lower supports78, 80 are coupled to the lower plate and upper supports 88, 90 arecoupled to the middle plate 56. The lower plate 76 and middle plate 56are coupled to one another to form cassette 50 as indicated by thedashed lines. The lower supports 78, 80 extend through apertures in thecooling plate 52. An atmospheric robot (not shown in FIGS. 7 a-f)delivers into and removes substrates from the load lock throughatmospheric opening 96 and door 68, and a transfer chamber robot (notshown in FIGS. 7 a-f) removes from and delivers substrates into theloadlock through vacuum opening 98 and door 99. As seen in FIGS. 7 a-f,the cooling plate 52 is coupled to the frame 64 and does not moverelative to the openings 96, 98. The cassette 50 (which includes thelower plate 76, lower supports 78, 80, the middle plate 56, and theupper supports 88, 90), is moveable relative to the openings 96, 98.

A condition when there are no substrates in the loadlock is illustratedin FIG. 7 a. This may be the condition at the beginning of a processingcycle. In one embodiment, a processing method includes supplying anunprocessed substrate 92 to the loadlock. As shown in FIG. 7 b, uppersupports 88, 90 are aligned with the opening 96 and an unprocessedsubstrate 92 has been inserted into the loadlock through an atmosphericopening from the direction indicated by the arrow. Next, the atmosphericopening door 68 is closed, the loadlock is evacuated and the cassette 50is raised to place the lower supports 78, 80 through openings 59 in thecooling plate 52 and into alignment with the vacuum opening 98 as shownin FIG. 7 c. Vacuum opening door 99 is opened so that a processedsubstrate 82 can be delivered from a transfer (or other processing)chamber (not shown) to the loadlock from the direction shown by thearrow, and placed on supports 78, 80.

The cassette 50 may then be lowered to place the processed substrate 82onto the cooling plate 52 for cooling, as shown in FIG. 7 d. Preferredembodiments may include structures such as pins 57 extending from thecooling plate 52 into openings 61 in the bottom of the middle plate 56.The pins 57 may act to ensure proper alignment of the cooling plate 52and middle plate 56 as well as providing a barrier to prevent asubstrate from sliding off of the cooling plate in a lateral direction,which may occur due to a gas pressure introduced in the chamber during acooling procedure. As can be seen in FIG. 7 d, the cooling plate 52 andmiddle plate 56 may be positioned so that the processed substrate 82 isessentially sandwiched between the plates. This promotes the efficientcooling of the processed substrate 82. In general, the closer the middleplate 56 is positioned to the processed substrate 82, the faster thecooling rate of the processed substrate 82. In one example, a 5 mm gapbetween the middle plate 56 and the processed substrate 82 provided acooling rate that was about 5 times faster than a 1 inch (˜25 mm) gap.

FIG. 7 d also shows that the unprocessed substrate 92 has also beenplaced into alignment for delivery through the vacuum opening 98 in thedirection indicated by the arrow. The unprocessed substrate is deliveredthrough the vacuum opening and then the vacuum door 99 is closed and thechamber vented so that another unprocessed substrate 92′ may be placedonto the upper support 88, 90 through the atmospheric opening, from thedirection indicated by the arrow, as illustrated in FIG. 7 e. Theventing may also be controlled to promote uniform cooling of theprocessed substrate 82. The cassette 50 may then be raised to lift theprocessed substrate off of the cooling plate 52 and into position to beremoved from the loadlock through the atmospheric opening 96 in thedirection indicated by the arrow, as shown in FIG. 7 f.

It should be appreciated that the above steps may be varied as desiredand that there are numerous different processing schemes that may beperformed according to embodiments of the present invention. Forexample, another processing embodiment may include heating theunprocessed substrate 92 in the loadlock prior to transferring it to thetransfer chamber. In such an embodiment the heating step is carried outand the heated, unprocessed substrate 92 is preferably delivered throughthe vacuum opening 98 to the transfer chamber prior to delivering theprocessed substrate 82 from the transfer chamber to the loadlock.

More detailed views of the cassette 50 and the cooling plate 52 areillustrated in FIGS. 8 and 9. The upper plate 54, middle plate 56, andlower plate 76 may be coupled together through side portions 77, 79. Theside portions 77, 79 may be separate pieces coupled together using pins89. Alternatively, the side portions 77, 79 may be a single unit and maybe integrated into one or more of the plates 54, 56 and 76.

As seen in FIG. 8, the lower supports 78, 80 are supporting processedsubstrate 82 above the surface of the cooling plate 52. Thisconfiguration may correspond to a load/unload condition where aprocessed substrate 82 is being loaded into or removed from theloadlock. In this embodiment the processed substrate 82 is transparent.The supports 78, 80 may have a variety of structures that can support asubstrate including, but not limited to a pin, bolt, screw or peg-likeshape. The tips of the supports may also have variety of structures. Forexample, as illustrated in FIG. 7 a, the tip of the supports 78, 80, 88,90 are rounded, whereas in FIG. 9, the tips of the supports 78, 80 areflat and include openings 81. As illustrated in FIGS. 8 and 9, oneembodiment preferably includes four outer pins 78 and two central pins80.

FIG. 9 illustrates the position of the lower supports 78, 80 after thesupports have been lowered to place the processed substrate 82 on thesurface of the cooling plate 52. The cooling plate 52 may be designed tohave one or more zones for preferentially controlling the temperature ofa substrate thereon. This may be accomplished by providing a pattern ofone or more channels or grooves 104 on its upper surface. The locationand number of grooves 104 is designed to control the contact areabetween a substrate and the surface of the cooling plate 52 to permitbetter temperature control during cooling. For example, if more grooves104 per unit area are located near the periphery of the cooling plate 52than near the center, an increased surface area of the substrate willcontact the cooling plate 52 near its center. If the center is a heattransmissive material such as, for example, a metal, then more heat willbe transmitted from the center of the substrate. The grooves 104 aredesigned to counter the thermal losses, which typically occur morequickly near the periphery of the substrate. This leads to a moreuniform temperature distribution across the substrate during cooling. Inone embodiment the grooves 104 may have a width of about 6 mm and adepth of about 1 mm. Other dimensions may be suitable for particularapplications.

Embodiments may also include a one or more coolant carrying channelsincorporated into or attached to portions of a cooling plate and amiddle plate in order to remove heat from the plate quickly. The coolantcarrying channels may be distributed along the cooling plate as desiredto yield different cooling characteristics for different portions of thecooling plate, in order to provide a more uniform temperaturedistribution across a substrate. FIG. 10 illustrates a cross-sectionalview of an embodiment of a cooling plate 106 including a number ofgrooves 104 and a coolant carrying channel 108 formed therein. FIG. 11illustrates an embodiment of a cooling plate 110 including grooves 104and a pipe or tube 112 as a coolant carrying channel connected(permanently or detachably) to the bottom of the cooling plate 110. Incertain embodiments, the middle plate acts like a second cooling plateto assist in cooling a processed substrate. FIG. 12 illustrates anembodiment of a middle plate 116 including a coolant carrying channel118 therein. FIG. 13 illustrates an embodiment of a middle plate 120having a pipe or tube 122 as a cooling carrying channel connected(permanently or detachably) to the top of the middle plate 120.

Embodiments may also include a cooling plate and a middle plate eachincluding a surface having multiple characteristics such as a differentsurface finish in different locations. For example, a dull and/or blackfinish (or other dark color finish) may accelerate cooling due togreater heat absorption than a reflective and/or smooth finish, whichwill reflect more heat back to the substrate. Anodizing or bead blastingall or part of the cooling plate can form a preferred high emissivityfinish that may accelerate cooling. As illustrated in FIG. 14, forexample, the surface of a plate 130 (such as a cooling plate and/or amiddle plate) may contain a high emissivity central area 131. As seen inFIG. 14, the high emissivity central area 131 of the plate 130 is viewedthrough a transparent substrate 132. The substrate 132 preferably has alarger size than the high emissivity area 131 (and a smaller size thanthe plate 130). In certain embodiments, in order to more uniformly coolthe substrate it is desirable to not provide the high emissivity region130 near the edges of the substrate 132. This is because the edges ofthe substrate 132 tend to cool more quickly than its center area, soproviding the high emissivity region 130 over the entire surface wouldlead to the edges of the substrate 132 cooling much faster than thecentral area. Such non-uniform cooling can cause undesirable stressesand/or warping of the substrate 132.

The top and bottom covers 70, 72 (FIG. 2) of the loadlock 30 may includeflanges 116 and o-rings 118, which are used to mount the top cover 70and lower cover 72 to the loadlock frame member 64. Top cover 70 mayalso include inlet/outlet vent 120, which may include a gas deliverypipe or tube through which a gas may be delivered to the interior of theloadlock. A variety of gases may be delivered to the loadlock dependingon the processing operation (cooling, annealing, preheating, ashing,etc.) to be carried out. In certain embodiments, it is preferred that acooling gas is delivered into the chamber upon venting to assist incooling a processed substrate on the cooling plate 52. Preferred coolinggases for use in the chamber include nitrogen and/or helium. Other inertgases including, but not limited to argon and neon could also be used.Certain embodiments utilize a mixture of helium and nitrogen atpressures of about 754-759 Torr nitrogen and about 1-6 Torr helium. Inone preferred embodiment, cooling gas is supplied to the chamber byventing the chamber at 3 Torr helium and 757 Torr nitrogen. This coolingscheme has been observed to provide a uniform and rapid cooling.Preferred embodiments may also include helium alone as the cooling gasdue to its inert nature and thermal conductivity. It is preferred thatthe substrate be cooled with a uniformity of about 100 degrees Celsiusor less along the substrate, even more preferably about 50 degreesCelsius or less. If desired a filter 122 (FIG. 2) may be positioned nearthe top of the loadlock to filter out undesirable particles and topromote uniform distribution of gas throughout the loadlock chamber. Thefilter 122 may be held in place by holder 124 and may be adjusted usingscrew 126.

In certain preferred embodiments, the lower supports 78, 80 extendthrough apertures in the cooling plate 52. Alternative embodiments mayutilize a lower support extending adjacent to the cooling plate insteadof through the apertures in the cooling plate. As illustrated in FIG.15, one such embodiment may include a support 136 adjacent to a coolingplate 138 including one or more movable arms 140 which may be loweredinto one or more grooves 142 in the cooling plate 138 in order todeposit a processed substrate 82 on the upper surface of the coolingplate 138.

Other embodiments may include a loadlock having components similar insome ways to those illustrated in 6 a, but including a single openingfor transferring substrates in and out of the loadlock and between theloadlock and a transfer chamber.

Several embodiments of cluster processing systems according toembodiments of the present invention are illustrated in FIGS. 16 and 17.FIG. 16 illustrates a system 158 which, according to one embodiment,includes a supply of unprocessed substrates from an unprocessedsubstrate cassette 162, which may be supplied to the loadlock 160 from asubstrate cassette and robot station 164 one at a time using a robot166. The loadlock 160 may have a similar structure to the loadlock 30shown in FIGS. 2-4 Once an unprocessed substrate is inside the loadlock160, the loadlock 160 is evacuated and the unprocessed substrate istransported to the transfer chamber 168 having a second robot 170therein. Once inside the transfer chamber 168, the unprocessed substrateis transferred between chambers for processing. In one embodiment, thesubstrate is first transported to chamber 172 for heating, then back tothe transfer chamber 168, and then to another processing chamber 174,which may be any other type of processing chamber such as, for example,a chemical vapor deposition (CVD) chamber, a physical vapor deposition(PVD) chamber, or an etching chamber. After treatment in a processingchamber 174, the substrate may be transported to the transfer chamber168 and then to another processing chamber 174. When the substrate isfully processed as desired, it is then delivered from the finalprocessing chamber to the transfer chamber 168 and back to the loadlock160. The processed substrate may then be cooled in the loadlock 160.Cooling may take place while the loadlock 160 is evacuated and may alsotake place as the loadlock 160 is vented. Once venting is complete andthe processed substrate is sufficiently cooled (such as, for example, toabout 100 degrees Celsius), the processed substrate may be removed fromthe loadlock 160 using the robot 166 and delivered to a processedsubstrate cassette 176 at the station 164.

Another embodiment of a processing system 178 in some ways similar tothat of FIG. 16 is illustrated in FIG. 17. However, the embodiment ofFIG. 17 includes two loadlocks 160 and five processing chambers 174, aswell as one heating chamber 172 and transfer chamber 168 having a robot170 therein. This embodiment may be particularly useful when theprocessing can be carried out quickly and throughput can be increased bysupplying more substrates to the system. As illustrated, the system 178includes a larger station 165 having more cassettes 162, 176 forsupplying unprocessed substrates to the loadlocks 160 and for acceptingprocessed substrates from the loadlocks 160 using the robot 167. Certainembodiments of the present invention may include a heater within theloadlock. When using such embodiments, it may be possible to eliminatethe heating chamber such as heating chamber 172 of FIGS. 16 and 17. Insuch a case an additional processing chamber 174 may be used if desired,and if only one loadlock 160 is used, the system will have sevenprocessing chambers. Depending on the desired processing steps and theplatform used, any number of processing chambers, loadlocks, and heatingchambers may be used. Certain platforms may also utilize more than onetransfer chamber.

Selected embodiments of the present invention can provide one or more ofa number of advantages. For example, in certain embodiments, a singleloadlock chamber can be used for both cooling processed substrates andheating unprocessed substrates. Various features also enable a largeglass substrate to be cooled or heated quickly, thereby increasing thethroughput of the system. Various aspects of the loadlock design mayhelp to control the temperature of a substrate on the cooling plate toprovide a more uniform temperature across the substrate or to provide aparticular temperature distribution across the substrate. For example,the heating device 94 may in certain embodiments be used during acooling operation in order to control the temperature distributionacross a substrate. By controlling the insulative properties of themiddle plate 56 and/or other portions of the loadlock, heat from theheating device 94 may be transmitted to a portion of a substrate inorder to control its temperature. In one embodiment, by keeping theouter edges of the substrate at a higher temperature than the middleregions of the substrate, the outer edges can be placed into compressionas the substrate cools, thus minimizing the risk of edge failures.Cooling the outer edges of a substrate at a slower rate than theinterior portions of the substrate may be accomplished in certainembodiments by directed an amount of heat from the heating element 94around the edges of the middle plate 56 to contact the outer edgeregions of the processed substrate on the cooling plate 52.

In addition, the time spent waiting during processed substrate coolingand unloading from the loadlock can be significantly shorter when usinga dual substrate cassette according to embodiments of the presentinvention, as compared to using a loadlock having a larger cassetteholding, for example, 12 substrates. In a system having a cassetteholding 12 substrates in the loadlock, it may take approximately 2minutes for the system to vent and another 8 minutes to unload thesubstrates from the loadlock after it has been vented when using a robotarm to unload each substrate. Certain embodiments of the presentinvention (which have a considerably smaller interior chamber volumethan a loadlock having a 12 substrate cassette therein) may preferablyaccomplish both the venting and removal of a processed substrate in atime of up to about a minute, or more preferably about 30 seconds. Inaddition, certain embodiments which have a heating element in theloadlock can heat a substrate quickly due to the relatively smallinterior volume in the loadlock and because the substrate can be locatedclose to the heater. Preferred embodiments can heat the substrate in atime of less than one minute, or more preferably about 30 seconds.

The faster venting, substrate removal, and/or heating time provided byselected embodiments of the present invention offer several advantages.First, the throughput of the system may, for certain types ofprocessing, be higher. Certain embodiments can permit a fast tact time,which is the time it takes one substrate to enter the system, beprocessed, and then exit the system. Second, the need to use a robothaving the greatest speed possible (for unloading the substrates) may bereduced because the system can have less down time. Using a slower speedrobot may improve the reliability of the processing system.

Depending on the processing steps to be carried out, it may in certainembodiments be desirable to have 0 or 1 substrate in the loadlock at anyone time. In other embodiments, it may be desirable to have up to 2substrates in the loadlock at any one time. Alternative embodiments maypermit more than 2 substrates to be located in the loadlock at any onetime. Selected embodiments of the present invention may achieve a highthroughput despite having fewer substrates in the system at any one timethan in certain other systems. For example, one batch processing systemhaving a substrate cassette in the loadlock may at certain times haveapproximately 40 substrates in the system, with 12 substrates in theloadlock, 12 substrates in a heating chamber, and 16 substrates beingprocessed in the other system chambers. Matching the number ofsubstrates in the loadlock and heating chamber can permit smoothsubstrate transferring due to a symmetrical layout of the system. Asystem according to certain preferred embodiments of the presentinvention may at certain times have approximately 15 substrates in thesystem, with 1 in the loadlock, 8 in a heating chamber, and 6 substratesin the other system chambers. These numbers may vary considerablydepending on the configuration of the various chambers in the system.Depending on the exact processing steps and their duration, due to thefaster insertion and removal of substrates, certain embodiments of thepresent invention may have a higher overall throughput per time periodthan a system that having a 12-substrate cassette in the loadlock.

The smaller size of the loadlock dual substrate cassette of certainembodiments of the present invention relative to the loadlock cassettesused in some other systems also enables to loadlock to be fabricatedfrom less material and to utilize smaller vacuum, elevator, powercomponents and the like. These smaller components can make the systemconsiderably less expensive than larger systems including multiplesubstrate cassettes within the loadlock.

Typical processing pressures used in the various chambers describedabove may range from about 10⁻⁸ Torr to several Torr and vary dependingon the chamber and the process steps (PVD, CVD, etching, annealing, etc)being performed. It is generally desired that the pressure differencebetween adjacent chambers be kept to a minimum or controlled whenadjacent chambers are in communication with each other in order tominimize contamination.

Embodiments of the present invention also include other types ofprocessing systems such as linear systems in which a substrate may betransported from a loadlock to one or more processing chamberssequentially and then to the same or another loadlock, depending on thesystem layout.

It will, of course, be understood that modifications of the presentinvention, in its various aspects, will be apparent to those skilled inthe art. A variety of additional embodiments are also possible, theirspecific designs depending upon the particular application. As such, thescope of the invention should not be limited by the particularembodiments herein described but should be defined by the claims.

1. A loadlock chamber, comprising: a chamber body having a first andsecond substrate access port; a first plurality of support pins movablydisposed in the chamber body and arranged to support a first substratethereon; a second plurality of support pins movably disposed in thechamber body and arranged to support a second substrate thereon; and acooling plate disposed in the chamber body below the first plurality ofsupport pins and stationary with respect to the chamber body.
 2. Aloadlock chamber, comprising: a chamber body having a first and a secondsubstrate access port; a first plurality of support pins movablydisposed in the chamber body and arranged to support a first substratethereon; a second plurality of support pins movably disposed in thechamber body and arranged to support a second substrate thereon; and acooling plate fixed to the chamber body at a position below the firstplurality of support pins.